Preparation of magnesium silicate/carbon composite for adsorption of rhodamine B

Abstract

A magnesium silicate/carbon composite was prepared by a simple hydrothermal method using sodium silicate, magnesium sulfate, glucose and sodium acetate as raw materials. The composite was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET to understand the morphological and chemical changes. It was found that the composite was composed of amorphous magnesium silicate and amorphous hydrothermal carbon with a layered porous structure and a specific surface area of 235 m² g⁻¹. Rhodamine B (RhB) was used as a simulated contaminant in water to assess the adsorption properties of the composite. The equilibrium adsorption capacity of the composite was found to be 244 mg g⁻¹, 27.48% higher than that of magnesium silicate. The adsorption of RhB onto the composite was affected by pH of the solution with the highest adsorption capacity corresponding to a pH of 9. The adsorption kinetics of RhB onto the composite could be better described by a pseudo second-order model. The adsorption process was found to be controlled by intraparticle-diffusion. The adsorption isotherm data matched better with that of the Langmuir model, confirming monolayer adsorption on the homogeneous surface. In view of its good adsorption capacity, the adsorbent prepared in this study has the potential of treating dye wastewater in practical applications.